/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.ignite.ml.selection.scoring.metric.regression;

import org.apache.ignite.ml.selection.scoring.metric.MetricValues;

/**
 * Provides access to regression metric values.
 */
public class RegressionMetricValues implements MetricValues {
    /** Mean absolute error. */
    private double mae;

    /** Mean squared error. */
    private double mse;

    /** Residual sum of squares. */
    private double rss;

    /** Root mean squared error. */
    private double rmse;

    /**
     * Initalize an instance.
     *
     * @param totalAmount Total amount of observations.
     * @param rss         Residual sum of squares.
     * @param mae         Mean absolute error.
     */
    public RegressionMetricValues(int totalAmount, double rss, double mae) {
        this.rss = rss;
        this.mse = rss / totalAmount;
        this.rmse = Math.sqrt(this.mse);
        this.mae = mae;
    }

    /** Returns mean absolute error. */
    public double mae() {
        return mae;
    }

    /** Returns mean squared error. */
    public double mse() {
        return mse;
    }

    /** Returns residual sum of squares. */
    public double rss() {
        return rss;
    }

    /** Returns root mean squared error. */
    public double rmse() {
        return rmse;
    }
}
